12-inch drivers for sub

Tony,
profound apologies if you thought that my post was in anyway having a go at you. Only the first part was in direct response to your question about the cross-over frequency. The idea of the row of dots was to try and separate the two sections of my post. Perhaps not too successful an idea.

One only has to look at the vast array of different loudspeaker designs to realise that there is no one best solution and that designers have their own interpretation of what is essentially the same problem.

Of all loudspeaker designs the bandpass seems to polarise opinions. The interesting thing for me is to try and discover what it is that makes opinions so divided.

Again to clarify my last post, the section below the dots was just some general rambling thoughts regarding the thread as a whole, not amied at any one person. Apologies for any distress or confusion I may have caused.

Steve

Steve,
As usual one the biggest problems with Forums is not being able to see the facial expressions and general body language of the third party.

I had in no way taken offense at what you had written, I was a bit worried that I had gone OTT with my previous post and was trying to mend a few fences, obviously not very successfully.

Next time I try to play Devils Advocate I will remove one horn.

Best Regards

Tony



Edited by: AJW

AJW wrote:

Deadbeat wrote:

Deadbeat wrote: However, it can be ironed out in many ways.

Exactly [img]smileys/smiley32.gif[/img]

Yep, make the cabs from the finest hand selected Russian Birch ply making sure all the joints are fully rebated etc. Finish off with 6 carefully applied coats of aldcrofts speaker paint and then wait till Nov 5th and burn the sh*tty things [img]smileys/smiley2.gif[/img]


You may not be able to polish a turd but you can roll it in glitter but at heart its still a turd.

I understand the sentiment. But the lumped component model is a good prediction of behaviour up to over 200Hz for suitable cabinet designs (ie avoiding extreme dimensions in chambers or ports). This stuff is understood by real acousticians like Berenak, Theile/Small etc. It is not any kind of gold-plated BS.

AJW wrote: I have no problems at all with BP6 on Sub but why anyone would want to run lower mids through them especially as there are much simpler ways of doing it is beyond me. Just because it can be done is no excuse for actually doing it.

The reason is: you get a more compact system for the same lower F3. There are other benefits too.

AJW wrote: Ialso hope that jsg goes on to build a stunning box that performs way beyond his wildest hopes and he can raise a single digit and proudly acclaim SEE you "Black Country Twat".

I have 3 such cabinets at home right now. All been gigged, never had any complaints. I'd like to direct you to my earlier comment:

jsg wrote: I've done this, built the cabinet, got the T-shirt.

I'd hate to think you selectively ignored that.
Edit: actually 4. I forgot about my car sub which kicks like no bandpass ever heard in a car.

AJW wrote: the simplest way of getting lower mids to sound natural is a direct radiator performing above the band that is influenced by any reflex enhancement. I have yet to be convinced otherwise.

Obviously an unported direct radiator is simpler. And if you are not convinced, fair enough. I am convinced, and I've done the necessary theory, modelling, cab building, measuring and listening to be convinced. Consequently, you're pretty unlikely to unconvince me. I hope you're OK with that.

AJW wrote: the phenomenon known as "The Hayes * affect"

I distinctly remember pointing out that once the top-end group delay was constant, the cabinet would need delay compensation, just like a horn bin does (A horn bin would otherwise be just as likely to suffer from the Haas effect). Here it is:

jsg wrote:
- Obviously, time align using a controller, just like you would with a horn bin.

It turns out that I mentioned it again, in my subsequent reply:

jsg wrote:
If you can get the group delay to be constant, then the behaviour is no different to a horn path delay, or simply standing further from the speaker.

I'm going to go out on a limb here and suggest that someone skilled enough in the art to know about the Haas effect ought to have been able to understand what I was trying to express in these two excerpts.

I'd like to leave with one parting throught. The effect of your crossover (passive, active, it doesn't matter) has a similar effect on the sound as the upper resonator of a bandpass.

BUTmost crossover filters are well dampedand do not exhibitaudible resonance or problematically large group delay variations, wheras most bandpasses are not well enough damped at thetop end and so they do ring and the group delay does tend to peak.

You can however design a bandpasstohave adequate damping of the top end. And then, there is essentially no difference in the sound from a reflex or sealed box with a 12 or 24dB/octave crossover.
Edited by: jsg

The fact that you are happy with the performance of the cabs is not evidence that the cabs do indeed perform in an adequate manner. We may have totally different aspirations.
Regardless of the science I can ultimately only rely upon my ears to say yes or no.
At the end of the day I am perfectly happy to accept you opinions at face value, I hope you can extend to me the same courtesy.

Tony

p.s. At the risk of repeating myself I do not have a problem with B.P. per se, its only when it is used outside its comfort zone (into the lower mids) that cause me concern.

Edited by: AJW

Tony.
I didn't see the relevance of your comments about bonfires. If you wanted to discuss the relative merits of cabinet design and construction material on combustibility you should have started a new thread. [img]smileys/smiley2.gif[/img] [img]smileys/smiley36.gif[/img] [img]smileys/smiley36.gif[/img]

I've got to get ready for a gig now so keep it civilised guys.

edited to insert text 'cause I clicked the wrong button [img]smileys/smiley5.gif[/img]

Edited by: Steve_B

AJW wrote: At the end of the day I am perfectly happy to accept you opinions at face value, I hope you can extend to me the same courtesy.

I believe I have done that, in spite of the poopy comparisons in your original comment, and the fact that you joined a thread in which science was being discussed, without any scientific angle.

Tapped horns and bandpass?

I think it's important to stick this thread in now.
The discussion starts from post #71
www.diyaudio.com/forums/showthread.php?s...page=25&pagenumber=3

'As usual one the biggest problems with Forums is not being able to see
the facial expressions and general body language of the third party.'

Keep this in mind gents, and things will not go astray.

jsg wrote:

AJW wrote: At the end of the day I am perfectly happy to accept you opinions at face value, I hope you can extend to me the same courtesy.

<div></div>
<div>I believe I have done that, in spite of the poopy comparisons in your original comment, and the fact that you joined a thread in which science was being discussed, without any scientific angle.</div>
<div></div>

The answer to my original question posted above is obviously "no".

It was quite interesting that in the discussion highlighted above by deadbeat that hardly any mention was made of which type of design actually sounds better!!!

Edited by: AJW

Actually, post 71 was when the protagonist posted his opinions on how his two boxes sounded subjectively.

The rest of the thread focuses on possible explanations of the sound and measured responses of both tapped and bandpass and the disparities between.

That's the pure objective viewpoint - that no sound can not be quantified or explained.
As you can see, there's a few pure objectivists in the thread (Gedlee, etc), but most are a healthy mix of both.

Deadbeat
Unfortunately as I became only too aware of many many years ago we all do seem to hear identical sounds in totally different ways, "ones man's meat is almost literally one man's poison".

I still stand by my assertion that it is advisable that no part of the vocal frequency range should ever have to be listened to through the medium of a resonant port *.

If other people have no problems with this then that's fine but for other people standing on the wayside it may be valuable for them to get the opposing view.

Tony

* Or for that matter through a folded horn.